The present disclosure is related to semiconductor devices. More particularly, the present disclosure is related to semiconductor devices on germanium-containing substrates.
Various benefits can be realized by reducing the dimensions of semiconductor devices. One benefit is the ability to increase the number of individual devices that can be placed onto a semiconductor substrate without increasing its relative size. Also, increasing the number of individual devices leads to increased functionality. Yet another benefit is increased speed of the individual devices as well as their collective arrangements. The semiconductor industry has been realizing these size-reduction benefits using silicon substrates. But, in addition to scaling, i.e., size reduction, other materials are being investigated to increase semiconductor device performance. One promising material for use in a variety of semiconductor and optoelectronic devices is germanium (Ge). Germanium has very high carrier mobility and generally superior transport properties, relative to other materials. For example, relative to silicon (Si), germanium's electron mobility is two-fold larger, and its hole mobility four-fold larger.